Monday, November 21, 2011
My Thoughts On Obesity
The conventional model of obesity is as follows: Eat more calories than you expend and you'll gain weight. To paraphrase my professor, it really is just a simple math equation. And for weight loss, burn more calories than you take in and you'll lose weight. That's not the part I disagree with. That is an established fact. But the problem is that conventional obesity paradigm ends there. Really?? That's it?? I'm paying for a top quality nutrition education, and we're not going to delve any deeper than that? I would expect this in a high school health class; you don't need to bother high schoolers with the finer details that they likely wouldn't even care about. But this is an advanced course in nutrition... I expect more than the "all you need to lose weight is a calculator" mentality.
This calories in, calories out model of obesity says that if you've gained weight, you've consumed more calories than you've burned, but it does nothing to explain why someone has consumed more than they've burned. Imagine walking into a room full of people. You ask someone, "Why are there so many people in this room?" And the response you get is, "Because more people entered the room than left it." That would be a stupid answer, something a 2nd grader might tell you when they first learn about addition and subtraction. But that is essentially the same as telling someone they got fat because they consumed more calories than they expended. It's obvious, but it doesn't really tell us anything about why that is the case. While excess caloric intake causes obesity, you can go much deeper than that (that's what she said).
Let's run through a quick history of obesity shall we? A little knowledge of the past is essential for a complete understanding of the present. In 1985, the earliest data we have for obesity in America, no state had an obesity rate of over 14%. Fast forward to 2010, and not one state has an obesity rate below 20%. Many states have rates over 30%. It is not at all a stretch to say, then, that obesity rates have more than doubled in the past 25 years.
While there is no concrete data before 1985, it is probably safe to assume that obesity wasn't a problem. Just watch any old movie, television show, or news footage, and you'll likely have a hard time picking out the obese people. Sure, they existed, but not in the numbers that they do today. And check out this ad from the 1800's, courtesy of Whole Health Source...
It's a product called "Fat-ten-u", designed to "make the thin plump and rosy with honest fleshiness of form." In other words, it makes you fat. This is fascinating on two levels. Firstly, it's interesting that women of that era actually wanted to be fat. Social norms have clearly changed. Just a little bit. But social aspects aside, the existence of this product indicates that women in the 1800's couldn't get fat if they tried. Imagine that! Was there a food shortage? Were they too busy to eat? Were they diligently tracking their caloric intake and expenditure on their iPhones? No, no, and... yes, maybe. There was plenty of food to go around, and I can't imagine their lives were as hectic as ours today. Yet they couldn't get fat if they tried. What gives?
If you want to go way back to ancient times, even prehistoric times, the fossil evidence shows that obesity was extremely rare. In some cases, like in Ancient Rome, being overweight was considered a symbol of power, and so nobles would deliberately overeat. But aside from those rare cases, people didn't generally gain weight. And again, food was plentiful. Even in hunter-gatherer times, food was normally plentiful. Tribes wouldn't choose to settle in an environment with no food, they weren't stupid. Modern tribes like the Kitavans reenforce this idea; they have more than enough food to feed themselves and plenty of free time, yet obesity is extremely rare.
The question is this: If food was plentiful throughout much of human history, why didn't we overeat and become fat? We didn't even know what calories were, but that didn't keep us from staying lean. And why do we overeat today, knowing all that we know about the caloric content of food? It is estimated that, on average, each of us eats a whopping 523 calories more today than we did in 1970, despite our ability to accurately track our caloric intake. If anything, our knowledge of calories has only made us consume more. In a sea of new low-fat crackers and cookies, 100-calorie packs, and skim milk, we are largely missing the point... we have forgotten completely about hunger and satiety.
Hunger and satiety are opposing forces in humans, along with all other mammals. Hunger, obviously drives you to eat, while satiety signals that you're full and that you should stop eating. When the system works correctly, your body will let you know when to eat and when not to eat. This is why, historically, we have had no problem maintaining a relatively lean body. As another example, just look at any wild animal and you'll see that they are almost never fat. Why? Because this biological mechanism of hunger and satiety is working effectively. When we gain weight by overeating, however, the hunger/satiety system has malfunctioned, and the true cause of obesity lies in finding what caused this system to break.
The answer to that question is a bit more complex, and I don't have a concrete answer. A variety of factors come into play, including behavioral, psychological, social, and physiological elements. But in a nutshell, here is my take. I believe it is largely a food quality issue; refined foods like sugar, industrial vegetable oils, and processed foods don't satiate us, and hence make us overeat. Most of us don't even eat real food anymore, even those of us who are trying to eat healthy. We opt for quick and convenient boxed foods over healthy fresh foods. We try to save calories by opting for fat-free crackers, or diet soda. And we've fallen for the fallacy that a low-calorie food is a healthy food. A lunch consisting of a 100-calorie pack of oreos, a diet soda, and a couple rice cakes sounds great until you're starving again an hour later. We need to come to terms with the fact that cookies and soda are, by definition, unhealthy foods, and there's nothing you can do to them to change that. Throughout human history, our diet has been made up of real, natural foods like fruit, vegetables, meat, fish, potatoes, full-fat dairy, nuts, seeds, and limited grains... foods that are near impossible to overeat. We as a society are so far removed from nature that we often don't see the obesity problem in this light. But when you take a few steps back and get a good look at it in the context of evolution and biological systems, it seems pretty obvious to me: processed food is killing us.